Fueled with liquid hydrogen and liquid oxygen, the S-IVB was powered by a single, restartable, J-2 engine.Ī single propellant tank was divided into two compartments by a common bulkhead. The S-IVB stage was restarted in low Earth orbit to send the Apollo spacecraft to the Moon.ĭeveloped by McDonnell Douglas, the S-IVB served as third stage for Saturn V rockets and as second stage for Saturn IB rockets. Payloads have included several interplanetary missions, including the Mars Reconnaissance Orbiter, the New Horizons Pluto probe, the Lunar Reconnaissance Orbiter, The Juno Jupiter orbiter, and the Mars Science Lander spacecraft. The length, with engine nozzles extended, is 12.68m. A Reaction Control System (RCS) handles attitude control during un-powered flight and roll control during powered flight. The main engine is gimbaled to provide attitude control during powered flight. Total propellant load for an Atlas V Centaur is 20,830kg. The engine is restartable and uses liquid oxygen and liquid hydrogen as propellants. Build by Pratt & Whitney, the RL-10A-4-2 features an extendable nozzle to improve performance. Power is provided by one or two RL-10A-4-2 engines. The Atlas V Centaur, sometimes known as the Common Centaur, is available in two versions, the Single Engine Centaur (SEC), and the Dual Engine Centaur (DEC). (An astronaut is included as a scale reference.) Both missions were launched on Atlas 5 Rockets. Illustration showing Centaur stages with the New Horizons Pluto probe and the Mars Science Lander spacecraft. Over 30 missions were flown between 19, including launching of the Pioneer Venus orbiter and multi-probe in 1978.Ītlas V Centaur and Interplanetary Payloads The Centaur D1-AR stage was used with Atlas SLV-3D and Atlas G rockets. Historic payloads included two Viking spacecraft to Mars in 1975, and two Voyager outer planet probes in 1977. The Centaur D-1T was flown seven times between 19. The Centaur D-1T stage was modified for use exclusively with the Titan-3E rocket. The Centaur D-1A was flown 6 times between 19. A D-1A was also used to send Mariner 10 on its way to encounters with Venus and Mercury. Launched on Atlas rockets, Centaur D-1A stages Launched the Pioneer 11 spacecraft toward Jupiter and Saturn. The Centaur D was flown 24 times between 19. Launched on Atlas rockets, Centaur D-1 stages Launched the Surveyor Lunar landers, Mariners 6, 7, 8,and 9, several Orbiting Astronomical Observatory (OAO) missions, as well as a number of communications and test satellites. (An astronaut is included as a scale reference.) Centaur D The Voyager configuration also included a solid rocket motor as an additional stage. Viking and Voyager interplanetary spacecraft, illustrated in stowed configuration, mounted on Centaur D1-T upper stages. Viking and Voyager Spacecraft with Centaur D-1T Stages

Centaur, 50 years after its first flight in 1963, still sees frequent use on Atlas 5 boosters. The Agena stage, first flown in 1959, would fly over 360 missions before being retired in 1987. Although periodically upgraded, upper stage families tend to remain in service for long periods of time. Centaur and IUS also served on multiple families of launchers. For instance, Agena was used on various Thor, Atlas and Titan rockets. Several upper stages have seen service on more than one booster. The Agena would provide the spacecraft with power, communications, and attitude control, as well as providing orbital maneuvering as needed. Many early American intelligence spacecraft, for instance, remained attached to their Agena upper stage throughout their operational life. Some upper stages remain attached to their payload and provide services long after reaching their initial orbit. Often, upper stage engines can be restarted several times while in space. Upper stages propel payloads on interplanetary trajectories, or into orbits higher than could otherwise be reached using a rocket booster. Illustration showing several upper stages.

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